index: tabs -> spaces

Tabs were causing formatting issues with <code> blocks, so just set the
entire file to indent using spaces.

Signed-off-by: Sean Cross <sean@xobs.io>

index.html

@@ -175,7 +175,16 @@
             </section>
 
             <section>
-				<h2>About LiteX and lxsocdoc</h2>
+                <h2>About LiteX</h2>
+                <ol>
+                    <li>Hardware Description Language embedded in Python</li>
+                    <ol>
+                        <li>Doesn't run Python in hardware!</li>
+                    </ol>
+                    <li>Emits Verilog (or Yosys netlists)</li>
+                    <li>Makes it easy to create a SoC</li>
+                    <li>Powers the LCA2020 video production setup</li>
+                </ol>
                 <aside class="notes">
                     Fomu uses LiteX, which is related to Migen.  This is a hardware description language
                     written in Python.  You write Python code and run the program, and it generates
@@ -203,7 +212,7 @@
             </section>
 
             <section>
-				<h4>SPI Bitbang Module</h4>
+                <h4>Case Study: SPI Bitbang Module</h4>
                 <pre><code class="python" data-trim>self.bitbang = CSRStorage(4)
 If(self.bitbang.storage[3],
     dq.oe.eq(0)
@@ -231,6 +240,20 @@ dq.o.eq(
 
             <section>
                 <h2>Aside: Python Docstrings</h2>
+                <pre><code class="python" data-trim>def _format_cmd(cmd, spi_width):
+    """
+    `cmd` is the read instruction. Since everything is
+    transmitted on all dq lines (cmd, adr and data), extend/
+    interleave cmd to full pads.dq width even if dq1-dq3 are
+    don't care during the command phase: For example, for
+    N25Q128, 0xeb is the quad i/o fast read, and extended
+    to 4 bits (dq1,dq2,dq3 high) is: 0xfffefeff
+    """
+    c = 2**(8*spi_width)-1
+    for b in range(8):
+        if not (cmd>>b)%2:
+            c &= ~(1<<(b*spi_width))
+    return c</code></pre>
                 <aside class="notes">
                     As an aside, Python has something called Pydoc and Docstrings.  These are
                     comments that go at the top of functions and classes that let you describe
@@ -242,7 +265,7 @@ dq.o.eq(
             </section>
 
             <section>
-				<h4>New Register Definition</h4>
+                <h2>New Register Definition</h2>
                 <pre><code class="python" data-trim>self.bitbang = CSRStorage(4, fields=[
     CSRField("mosi", description="Output value for MOSI..."
     CSRField("clk", description="Output value for SPI CLK..."
@@ -266,7 +289,7 @@ dq.o.eq(
             </section>
 
             <section>
-				<h4>Refactored SPI Bitbang</h4>
+                <h2>Refactored SPI Bitbang</h2>
                 <pre><code class="python" data-trim>If(self.bitbang.fields.dir,
     dq.oe.eq(0)
 ).Else(